Structural phases formed by NO2/CO co-adsorption on Au{111} surfaces

Area of Science:

• Surface Science
• Materials Science
• Physical Chemistry

Background:

• Understanding molecular interactions on metal surfaces is crucial for catalysis and materials design.
• Gold surfaces, particularly Au{111}, are model systems for studying adsorption phenomena.

Purpose of the Study:

• To investigate the co-adsorption of nitrogen dioxide (NO2) and carbon monoxide (CO) on a Au{111} surface.
• To characterize the resulting molecular overlayer phases and their structural properties.

Main Methods:

• Low-temperature scanning tunneling microscopy (LT-STM) was employed to visualize molecular arrangements.
• Ultra-high vacuum (UHV) conditions were maintained throughout the experiments.

Main Results:

• Formation of a (√7 × √7)R19.1° phase with a 3:1 NO2:CO stoichiometry under NO2-rich conditions.
• Co-existence of this phase with other phases (2:1 and 1:1 NO2:CO stoichiometries) and bare Au surface under CO-rich conditions.
• Observation of chirality in individual domains of the (√7 × √7)R19.1° phase.

Conclusions:

• The study reveals complex co-adsorption behavior of NO2 and CO on Au{111}.
• The identified phases and their chiral nature offer insights into surface self-assembly and molecular ordering.